Single-atom Fe anchored graphdiyne for high-efficiency nitrate-to-ammonia conversion under ambient conditions

The electrocatalytic conversion of wastewater nitrate (NO₃^-) to ammonia (NH₃) under industrial-grade current densities at ambient conditions presents a sustainable alternative to the energy-intensive Haber-Bosch process, yet remains fundamentally challenging. Here, a highly efficient NO₃^- to NH₃ electrocatalyst with single Fe atoms dispersed on graphdiyne (GDY) is constructed through an <i>in situ</i> growth method. Experimental analysis demonstrates the formation of high-density atomic active sites on GDY, ensuring the high intrinsic activity of the electrocatalyst. Besides, the newly formed sp-C-Fe chemical bonds bridged GDY and Fe atoms providing a well-defined channel for selectively and efficiently transferring electrons from the active sites to the reactants/key intermediates, allowing for selective NO₃^- activation and efficient protonation. This atomic-scale electronic modulation enables exceptional nitrate reduction performance, achieving record-high faradaic efficiency (45.48%) and ammonia yield (202.34 μmol h^-1 cm^-2) while maintaining operational stability.